Electrically operated truck and battery charging control therefor



Jan. 30, 1951 F. E. BURGER 2,539,987 ELECTRICALLY-OPERATED TRUCK ANDBATTERY CHARGING CONTROL THEREFOR Filed Jan. 17, 1947 IN veN r0 RPatented Jan. 30, 1951 ELECTRICALLY OPERATED TRUCK AND BATTERY CHARGINGCONTROL THERE- FOR- Frank Edward Burger, Warren Row, near Reading,England, assignor to Lansing-Bagnall Limited, islewerth, Middlesex,England, a British company Application January 1'7, 1947, Serial No.722,517 In Great Britain September 19, 1946 Section 1, Public Law 690,August 8, 1946 Patent expires September 19, 1966 4 Claims.

This invention comprises improvements in or relating toelectrically-operated trucks. Under the term trucks are included allwheeled vehicles, especially those intended for use in warehouses andthe like for stacking or transporting goods from place to place andportable cranes for lifting purposes. The invention relates tobattery-operated motor-driven trucks. A limitation upon the use of suchtrucks arises from the necessity of charging the batteries frequently.When a large number of trucks are to be employed it becomes possible toinstall special charging plant but if only one or two trucks are neededin a small warehouse the charging plant constitutes an undue overheadexpense, which it is an object of this invention to avoid.

According to the present invention, a truck is provided with a battery,a traction motor which is capable of acting also, if suitably driven, asa dynamo for charging the battery, and a mains motor capable of beingoperated from electric supply mains, in combination with means forrendering the drive of the truck wheels ineffective and for operatingthe traction motor by the mains motor when desired.

The following is a description by way of example of one form of truck inaccordance with the invention, reference being made to the accompanyingdiagrammatic drawing which shows the electrical connections of thevarious parts:

A truck is provided accordin to the invention which is of any desired orsuitable mechanical construction having a chassis and supporting wheels,means for supportin an electric battery, an electric traction motor anda controller. The rotating portion of the electric traction motor isindicated in the drawing at H and operates a shaft I2 which is connectedthrough a clutch comprising two parts i3, M, to a second shaft [5 whichoperates one or more of the supporting wheels, indicated in the diagramat It. It will be understood that the wheels if; can be connected to theshaft l5 through a reduction gear if desired. A second (mains) motor iiis mounted in line with the motor I I upon the shaft !2. This is shownas a three-phase motor and is connected by lines [8 through a switch 59to a plug 26 on the truck. The plug 23 can be connected by a flexiblelead to any desired mains supply when it is desired to operate the motorl as a dynamo.

For driving the truck the motor i i is operated by a battery 2! one poleof which is connected to the motor directly by a line 22 and the otherpole of which is connected by a line 23 to a rheostat 24 provided with aseries of contacts 25 and a movable control member 26 capable of movingover the contacts 25 and varying the amount of the resistance 24 whichis in circuit. From the rheostat 24 a. line 21 leads to a series fieldwindin 28 of the motor I I and thence to the other terminal of thearmature thereof. By these connections the motor can be operated fromthe battery and the truck driven.

The rheostat 24 is provided with an ofi' con tact 29 and this isconnected by a line 30 to the contacts 3! of a battery-charging cut-out,which contacts can be connected by a contact member 32 to a series coil33 of the cut-out and thence by line 3-1. and resistance 35 to a shuntfield winding 36 of the motor II. The other terminal of the shunt fieldwinding is connected by a line 31 to a contact 38 capable of beingclosed by an additional switch arm 39 of the switch i9, and connectedwhen so closed by a line 40 to the line 22, and so to the terminal ofthe motor I I.

In operation, if it is desired to charge the battery the truck is drivenup to a position where the plug 20 can be connected by a flexible leadto a mains supply and is plugged into the mains. The movable member 26of the control rheostat 24 is moved to the 0 contact 29 and the switchi9 is closed. Closing of the switch 19 automatically disconnects theclutch l3, [4, so that operation of the shaft l2 by the motor I! willnot drive the truck. This automatic disconnection of the clutch iseffected by interlocking means which are shown diagrammatically in thedrawing as comprising a rod 4| on the switch l9 connected by abell-crank lever 42 to a link 43, the link 43 being connected by afurther bell-crank lever 44 to themovable member 14 of the clutch. Anysuitable interlocking means between the switch and the clutch may,however, be adopted.

As soon as the switch I9 is closed the motor H is driven by the motoril. At the same time the shunt winding 36 is placed in circuit byclosing of the contacts 38, 39 on the switch I9. The cutout contacts 32,3| are closed by the resulting energisation of a shunt coil 45 of thecut-out which is connected between the lines 34 and 31. The moving ofmember 26 to the contact 29 will conne-ct lead 3E3 and one of thebattery-charging cutout terminals 3i to battery lead 23, thebatterycharging cut-out switch 32 being normally open. The closing ofterminals 38 and 39 of switch i9 will connect shunt winding lead 3? tolead 43 and battery lead 22, and will connect the leads [8 of mainsmotor I l to the supply connection 20. Assuming a source of power atsupply connection 20, mains motor I! will then begin to rotate, drivingtraction motor II by means of shaft l2. A voltage will thus be producedby said traction motor H operating as a dynamo and will appear acrossthe opposite armature terminals thereof. A current will be caused toflow by said voltagethrough the shunt winding 36 by the following path:from one terminal of the traction motor armature through series windin28. lead 21, lead ,3 d6, resistor 35, shunt winding 36, lead 37,terminals 38 and 39 of switch l9, lead 40 and lead 22 back to theopposite terminal of the traction motor armature. Thus, the tractionmotor ll, acting essentially as a self-excited shunt wound dynamo willbuild up to a voltage sufiicient for charging storage battery 2|. Whensuch voltage is reached, the current flow through cut-out coil 45 inparallel with shunt winding 36 and shunt Winding resistor 35 will closebattery cut-out switch 32, thus applying the voltage produced by thetraction motor I I to battery lead 23 to charge the storage battery.Consequently the motor ll operates as a dynamo and charges the battery2|, the charging current proceeding from the line 21 through the cut-outcoil 33 by way of a connection 46, the rheostat resistance 24; being outof the circuit so that no resistance to charging is olfered. The amountof the resistance 35 is preferably adjustable so that the chargingcurrent is of such an amount that the mains motor can be set runningwhen the operator goes ofi shift and left running until the truck isrequired again.

for use, when the battery will be fully charged.

I claim:

1. In a vehicle the combination of a traction motor, a storage batteryfor operating the traction motor as a motor, a transmission from thetraction motor to a road-wheel of the vehicle, a

clutch in said transmission, a clutch-operating n means, a series fieldwindin on the traction motor, a shunt-field winding on the tractionmotor to enable it to actas a dynamo if suitably driven, a mains-motordisposed on the same side of the clutch as the traction motor adapted todrive said traction motor as a dynamo, a supply connection for the mainsmotor, switch means onthe vehicle for closing said supply connection,and mean interlocking the clutch-operating mean and the switch meanswhereby when the switch means closes the supply connection the tractionmotor is necessarily disconnected b the clutch from the road wheel.

2. In a vehicle, the combination of a traction motor, a series windingfor said motor for operation thereof as a motor, a shunt winding forsaid motor for operation thereof as a dynamo, a storage battery, a roadwheel, transmission means including a clutch between said traction motorand said road wheel, a mains motor on the same side of the clutch as thetraction motor adapted to drive said traction motor as a dynamo,variable resistance means in series arrangement with said.

traction motor armature, a battery-charging cutout in series arrangementwith said traction mo.

tor armature and operative. in response to the.

voltage produced by said motor when operating as a dynamo, and switchmeans adapted to con,- nect selectively said storage battery to thetraction motor armature through said variable resistance means tooperate said traction motor as a motor, and to connect said storagebattery to the traction motor armature through said battery-chargingcutout to operate said traction motor as a dynamo, said battery-chargincutout closing its circuit only when said motor shunt winding isenergized and the voltage produced by said traction motor operatin as adynamo is greater than the voltage produced by said storage battery, andmeans interlocking said switch means and said clutch to ensure that whensaid shunt winding is energized the traction motor is necessarilydisconnected from the road wheel, said interlocking means including amechanical connection between said switch means and said ch.

3. In a vehicle the combination of a traction motor, a storage batteryfor operating the traction motor as a motor, a transmission from thetraction motor to a road-wheel of the vehicle, a clutch in saidtransmission, a clutch-operating means, a series field winding on thetraction motor, a shunt field winding on the traction motor to enable itto act as a dynamo if suitably driven, a mains motor disposed on thesame side of the clutch as the traction motor adapted to drive saidtraction motor as a dynamo, a supply connection to the mains motor, aswitch on the vehicle for closing said supply connection to the mainsmotor, a switch in the shunt winding circuit, interlocking means betweensaid switch in the shunt field winding circuit and said switch forclosing said supply connection to ensure that said switch in the shuntfield winding circuit is closed when the supply connection to the mainsmotor is closed and opened when it is opened, and means interlocking theclutch operating means and the supply connection switch whereby when theswitch means closes the supply connection the traction motor isnecessarily disconnected by the clutch from the road wheel.

4. In a vehicle the combination of a traction motor, a storage batteryfor operating the traction motor as a motor, a transmission from thetraction motor a road-wheel of the vehicle, a clutch in saidtransmission, a clutch-operating means, a series field winding on thetraction motor, a shunt field winding on the traction motor to enable itto act as a dynamo if suitably driven, a mains motor disposed on thesame side of the clutch as the traction motor adapted to drive.

said traction motor as a dynamo, a supply connection to the mains motor,a switch on the vehicle for closing the supply connection to the mainsmotor, a switch in the shunt windin cir-,

cuit, variable resistance means having a control handle in series withthe traction motor armature, said control handle bein constructed whenmoved to the off position to close a charging circuit, said chargingcircuit including a battery charging cut-out in series with said switchin the shunt field circuit of the traction motor, interlocking meansbetween said switch in the shunt field winding circuit and said switchfor closing said supply connection to ensure that said switch in theshunt field winding circuit is closed when the supply connection to themains motor is.

REFERENCES CITED The following references are of record in' the file ofthis patent:

UNITED STATES PATENTS Number Name Date 676,965 Sachs June 25, 19012,170,546 Candor et a1. Aug. 22, 1939 FOREIGN PATENTS Number CountryDate 711,269 France...,...... Sept. 7, 1931.

Certificate of Correction Patent No. 2,539,987 a January 30, 1951 FRANKEDWARD BURGER It is hereby certified that error appears in the printedspecification of 'ng correction as follows:

the above numbered patent requim Column 4, line 29, after the Word motorinsert to and that the said Letters the same may conform to the recordof the case in the Patent Office.

Signed and sealed this 27th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Patent should be read as corrected above, so that Certificate ofCorrection Patent N0. 2,539,987 January 30, 1951 FRANK EDWARD BURGER Itis hereby certified that error appears in the printed specification ofthe above numbered patent requiring correction as follows:

Column line 29, after the word motor insert to and that the said LettersPatent should be read as corrected above, so that the same may conformto the record of the case in the Patent Ofiice.

Signed and sealed this 27th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

